High throughput is required in a portable wireless communication apparatus that have been spread recently. A PLL (Phase Locked Loop) circuit operating in a high frequency band is required as a frequency synthesizer in wireless communication.
The PLL circuit includes a frequency divider for dividing a high frequency band signal to a low frequency band signal. An ILFD (Injection Locked Frequency Divider) capable of operating at a high speed and with low power consumption in a high frequency band, which is, for example, not lower than 10 [GHz], is used as a divider (for example, see NPL 1). The injection locked frequency divider shown in NPL 1 will be described later with reference to FIG. 11.